1. Field of the Invention
This invention relates to multistable structures. More specifically, the invention is an active multistable device that can produce a change in twist when actuated.
2. Description of the Related Art
Many articulating and morphing structures use multiple parts and often use complicated actuation mechanisms such as hydraulic actuators, screws, or other devices to provide geometric change in the structure through the use of hinges, telescoping sections, and other mechanisms. For example, in many fixed wing aircraft, the wings provide stable lift, while hydraulically-operated flaps change lift and drag, and control is accomplished by moving the rudder and ailerons, which are also hydraulically operated.
In an effort to simplify and lighten structures, components that are both structural and can change shape to meet some change in operational needs, have been investigated. Many of these concepts depend on a continuous supply of power to piezoceramic or shape memory alloy (SMA) actuators to deform the structure elastically from its natural, and unique, equilibrium configuration to a ‘near-by’ configuration. However, if a structure that possessed multiple equilibrium configurations, i.e., a multistable structure, was used, power would be needed only to change the shape, not to hold the structure in the alternative shape.